Forecasters predict highs in the mid-60s (17-19C) and they are not expected to cool down until Saturday at the earliest.

International Olympic Committee spokesman Mark Adams says it is "always a constant battle for winter sports" to maintain optimal conditions when the weather warms up. He says they "are relaxed, but will watch the situation" as the days progress.

The outdoor events, including slopestyle skiing and biathlon, remain on schedule.

Sochi 2014 spokeswoman Aleksandra Kosterina says they have not had to tap into the snow reserves they are storing on the mountain.

She said: "We are not worried, but at the same time we are ready for taking measures if there is a need."